Contour attachment



Dec. 7, 1954 E. P. BULLARD I 2,696,135

CONTOUR ATTACHMENT 4 Sheets-Sheet 1 Filed 5, 1950 z I l INVEN TOR. [Jakart Dec. 7, 1954 a E. P. BULLARD m ETAL 2,696,135

CONTOUR ATTACHMENT Filed Aug. 5, 1950 1 4 Sheets-Sheet 2 FlqA- Dec. 7, 1954 Filed Aug. 5, 1950 E. P. BULLARD III.

ETAL

CONTOUR ATTACHMENT FIG.9

FIG. 8'

4 Sheets-Sheet 4 FlG.ll

FIG. 10

INVENTOR.

EDWARD P. BULLARD III JAMES E. ETTORRE United States Patent-O CONTOUR ATTACHIMEN T Application August 5, 1950, Serial No. 177,814

2 Claims. (Cl. 82-12) This invention relates to machine tools, and particularly to a new and improved forming attachment for lathes and the like for facilitating the turning of contours on work.

i In general, lathes are adapted to feed a cutting tool along two intersecting paths normally at right angles to each other. By engaging the feeds for both paths simultaneously, the tool is caused to move along a path at forty-five degrees to the horizontal such for example as shown in Patent 2,355,625.

Usual practice in employing cams and followers for contour Work with lathes of the above-referred-to type is limited to relatively flat curves, i. e., curves having surfaces, the angles to the vertical and horizontal of which are substantially large. When curves to be formed have surfaces which lie near the vertical and horizontal, excessive stresses and strains are encountered which limit the accuracy of reproduction, as well as over-burden the machine.

The principal object of this invention is to provide a forming attachment that will overcome the above referred-to difliculties.

Other objects are to provide a forming attachment that will require the tool to move at favorable angles relatively to the vertical and horizontal sothat relatively steep curves can be formed with ease; the provision of such a forming attachment in which a desired contour may include nearly vertical and nearly horizontal portions and still be produced by a cam having a favorable contour for facile operation of the machine; and the provision of such an attachment in which a cam plate is provided with a. cam track having relatively flat surfaces to produce a contour having relatively steep surfaces.

The above, as well as other objects and novel features of the invention will become apparent from the following specification and accompanying drawings, in which:

Figure 1 is a sectional elevational view of apparatus embodying the principles of the invention;

Figure 2 is a section taken substantially along line 2-2 of Pi 1;

Fig ure 3 is an end view of Fig. 1 along lines 3-3;

Figure 4 is a sectional view taken substantially along line 4-4 of Fig. 1;

Figure 5 is a diagram showing how the cam tracer is laid out;

Figures 6 and 7 are modifications of the apparatus shown in Figs. 1 to 5;

Fig. 8 is an elevational view of one of the elements forming part of the invention;

Fig. 9 is a sectional elevational View taken substantially along line 99 of Fig. 8,

Fig. 10 is an elevational view of a cam forming part of the invention; and

Fig. 11 is a sectional elevational view taken substantially along line 11-11 of Fig. 10.

' Referring to Figs. 1 and 2, a tool block 10 is provided with a dovetail bearing 11 that is adapted to engage a mating bearing surface formed in one face of va turret of a machine tool. The block 10 is provided with an opening 12 extending longitudinally therethrough forming a channel-shaped structure in a manner to receive a lever 13 that is pivoted on a pin 14 fixed in the side walls of, and extending through the channel-shaped opening 12 within the block 10. A cam plate 15 is also mounted in the opening 12 along side the lever 13 and is adapted to be reciprocated for a purpose to be described later. In order for the cam plate 15 to reciprocate, an elongated Patented Dec. 7, 1954 opeliiilg 16 is provided that prevents interference by the pln The lever 13, at its forward end, is provided with a tool bit 17 that includes a cutting nose 18. In order to provide stability to the pivoted lever 13, the block 10 includes separated ears 19, 20 (Figs. 1 and 4) having aligned openings through which a clamping bolt 21 is adapted to pass and be tightened.

Since the curve to be formed on the work includes horizontal as well as vertical components, movement of the turret which carries the assembly is preferably along a forty-five degree path relatively to the horizontal which is a compromise or average of the extremes of the contour or curve to be produced. Obviously, if no other agencies were present, this movement along a forty-five degree path would cause the tool 17 to move along a parallel path. The cam plate 15, however, is provided with a cam track 22, which when plate 15 is moved rightwardly as viewed in Fig. 1, causes lever 13, through a cam roller 23, to pivot about pin 14. The movement of the cam plate 15 rightward, and the forty-five degree path along which the tool block 10 is moved, enables the use of a cam track 22 having relatively flat surfaces compared to the contour to be produced on the work as will be evident from the following.

Since the assembly including block 10, lever 13 and cam plate 15 moves along a forty-five degree path relatively to the horizontal, restricting the cam 15 against horizontal movement to the left as viewed in Fig. 1, will cause the tool tip 18 to produce the desired contour with a cam track 22 having a flatter curve than the desired contour However, in order to further flatten the surfaces of the cam track 22, the cam 15 is moved rightwardly at the same rate at which the assembly is moved leftwardly by the descending movement of the turret along the forty-five degree path.

This rightward motion of cam 15 is produced by employing a driving block 23' that engages an ear 24 integral with the cam plate 15. The block 23 is attached to a tool block in a tool head adapted in the present embodiment to be moved along a forty-five degree path relatively to the horizontal and in the present embodiment normal to the path of motion of the turret. Accordingly, no relative movement occurs between 23 and 24 during the actual cutting of the contour.

When the cam roll 23 reaches the righthand end of the cam path 22, the desired contour on the work will have been completed. In order to return the tool tip 18 to its starting point to repeat the contour, the cam plate 15 is provided at its rightward end with a plate 25 rigidly attached thereto. tends through a passage 27 within the block 10 in parallelism with plate 15. The end of rod 26 opposite that fixed to plate 25 is provided with an abutment 28, and a spring 29 encircling the rod 26 is held between the abutment 28 and another abutment 30 fixed to the block 10. The construction and arrangement are such that when the contour has been formed, and the tool block 10 is traversed upwardly sufliciently to clear the Work, ear 24 becomes disengaged from block 23, and spring 29 returns the cam plate 15 to its starting position, thereby returning cutting tip 18 to its starting point. At the same time, the tool block holding block 23 is traversed leftwardly and upwardly to its initial position where it re-engages ear 24.

Referring to Fig. 5, the manner of laying out cam track 22 is as follows. Since the motion of the assembly is at forty-five degrees, such a line is drawn through the pivot pin 14 of lever 13. With a radius equalling the distance from pivot pin 14 to the center 31 of the radius of nose 18, an arc is struck which intersects the locus of the roll 23 at its starting point. With this original radius, other arcs are struck at equal intervals along the forty-five degree line through pivot pin 14. With the intersection of these arcs with the locus 'of the point 31, other arcs are struck having a radius equal to the distance from point 31 to the starting point of roll 23. These last arcs intersect the first at points 32, 33 and 34.

By dropping vertical lines from points 32, 33 and 34 a distance equal to the overall amount of vertical motion of the assembly in each instance, and by constructing horizontal lines at the ends thereof equal to the addi- A rod 26 is fixed to plate 25 and ex-- J tional horizontal distance of movement of the cam plate 1 5 by virtue of the action of driving block 2-3, the true locus of the roll 23 will be determined.

Referring to Figs. 6 and 7', a modified construction is disclosed in which positive engagement at all times is maintained between the means for moving the cam in both directions horizontally, as distinguished from the releasable connection provided by ear 24 and block 23' of Figs. 1 to 4. This construction eliminates the spring return mechanism shown in Fig. 1.

The righthand end of cam 15 is provided with a slot 35 adapted to engage a roll 36- fixed to an extension 37 of a shank 38 held in a tool block 39. With this arrangement, the movement of the tool block 10 and the block 39 along forty-five degree paths at right angles to each other produces the desired relative movement while at the same time maintaining a positive engagement between the blocks 39 and 10 during the cutting operation. The arrangement in Fig. 7 shows the parts in posi tion at the beginning of the operation. When the cut has been completed, the roll 36 is at the bottom of slot 35, and to reset the apparatus the block 10 is traversed vertically upwardly to clear the work, but not enough to disengage slot 35 and roll 36 Block 39 is then traversed leftwardly and upwardly until block 39 is in its starting position, and block 10 is traversed rightwardly to its starting position.

Although the various features of the improved forming attachment have been shown and described in detail to fully disclose two embodiments of the invention, it will be evident that numerous changes may be made in such details and certain features can be used without others, without departing from the principles of the invention.

What is claimed is:

1 Contouring apparatus for a machine tool comprising in combination, a main tool block adapted to be moved along a predetermined rectilinear path which lies at an angle between but substantially different from the extreme angles of the contour to be produced, said main tool block being provided with a channel-shaped passage extending longitudinally therethrough; a pivot pin extending through said channel-shaped passage and fixed in the side walls thereof; a lever pivoted on said pin; a cutting tip held by said pivoted lever; a cam roller on said pivoted lever; a cam plate reciprocably mounted within said channel-shaped passage and provided with an elongated opening through which said pivot pin passes; a cam path in said cam plate, the form of which is dependent upon simultaneous effective components of movement of said main tool block and said cam plate in opposite directions, and within which cam path the cam roller on said pivoted lever extends; an abutment car on said cam plate; an auxiliary, independently movable tool block adapted to be moved along a path in a direction having a component of movement opposite to a component of move ment of said main tool block; and means on said auxiliary tool block adapted to engage said abutment ear on said cam plate, whereby during a contouring operation, said lever is pivoted in accordance with the contour of said cam path and the rate of relative movement of said main and auxiliary tool blocks.

2. Contouringapparatus for a machine tool comprising in combination, a main tool block adapted to be moved along a predetermined rectilinear path which lies at an angle between but substantially different from the extreme angles of the contour to be produced, said main tool block being provided with a channel-shaped passage extending longitudinally therethrough; a pivot pin extending through said channel-shaped passage and fixed in the side walls thereof; a lever pivoted on said pin; a cutting tip held by said pivoted lever; a cam roller on said pivoted lever; a cam plate reciprocably mounted within said channel-shaped passage and provided with an elongated opening through which said pivot pin passes; a cam path in said cam plate, the form of which is dependent upon simultaneous effective components of movement of said main tool block and said cam plate in opposite directions, and within which cam path the camroller on said pivoted lever extends; a rod attached to said cam plate and extending into a. passage within said main tool block; a spring associated with said rod for urging said cam plate toward a starting position; an abutment ear on said earn plate; an auxiliary, independently movable tool block adapted to be moved along a path in a direction having a component of movement opposite to a component of movement of said main tool block; and means on said auxiliary tool block; adapted to engage said abutment car on said cam. plate, whereby during a contouring operation, said lever is pivoted in accordance with the contour of said cam path and the rate of relative movement of said main auxiliary tool blocks.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 179,000 Coriell June 1876 699,382 Gallagher May 6, 1902 1,678,924 Stridberg July 31, l928 1,856,196 Smith May 3, 1932 1,938,050 Smith Dec. 5, W33 1,973,801 Dunstan a- Sept. 18, 1934 2,001,586 Rupple May 14, 1935 2,388,265 Johnson Nov. 6, 1945 2,499,509 Kendall Mar. 7, 1950 2,540,520 Hoern Feb. 6, 1951 

